An NAND type flash memory spreads as a device for storing large capacity data. Currently, a storage device is made fine to progress a reduction in a cost or an increase in a capacity per bit.
On the other hand, it is also expected to practically apply a new storage device (hereinafter referred to as a memory) based on a different operation principle from a floating gate type flash memory according to the related art.
For example, a two-terminal memory represented by an ReRAM (Resistive Random Access memory) is considered to be promising as a next generation memory in respect of an easiness of a low voltage operation, high speed switching and a refinement, or the like. Examples of the two-terminal memory include a memory using an amorphous silicon layer (which will be hereinafter referred to as an amorphous silicon layer or abbreviated as an a-Si layer) in a variable resistive layer. Referring to the two-terminal memory, a conductive filament is generated in or is made to disappear from the amorphous silicon layer so that a resistance is reversibly varied. In order to stably operate the two-terminal memory, it is demanded to enhance a stability of the conductive filament generated in the amorphous silicon layer, thereby improving a data retention property.